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Finding the Fourth Proportional to 138.78, 208.17 and 53.22

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Solution

The fourth proportional to 138.78, 208.17 and 53.22 is: 79.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 208.17 = 53.22 : x
  2. Step 2: Convert to fraction form
    138.78/208.17 = 53.22/x
  3. Step 3: Cross multiply
    138.78x = 208.17 × 53.22
  4. Step 4: Simplify right side
    138.78x = 11,078.81
  5. Step 5: Solve for x
    x = 11,078.81/138.78
  6. Step 6: Final answer
    x = 79.83

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.